Transcript for Fear Growing in the Middle East Over Syria, Gas Masks Handed Out in Israel

have breaking news. The president has moved the nation one step closer to military action against syria. He said he is certain that the order to fire those chemical weapons came directly from the syrian government. And he seemed to leave little doubt that america is moving toward action. The mid east region is on a new kind of alert tonight and abc's martha raddatz is there in jerusalem. Reporter: Thousands of syrians fleeing damascus as president obama leaves no doubt tonight in an interview with pbs that syria's president assad has crossed a red line. When countries break international norms on weapons like chemical weapons that could threaten us, they will held accountable. Reporter: The president said he has not yet made a decision to strike, but if one is launched, it would be aimed at preventing another chemical attack, not in taking sides in syria's bloody civil war. There are dozens of potential targets, but likely among them facilities storing vehicles which could launch chemical weapons like this storage depot near damascus. The president wants to prevent assad from using chemical weapons on his people but he can't hit the chemical weapons storage sites directly. Reporter: If the u.S. Wants to take aim on the military, it could strike the vital mezze airfield or lock on a symbolic target like the ministry of defense in damascus. As syria waits, so does israel. Today in jerusalem, families stocked up on gas masks, fear a retaliatory strike. If america does act, officials say the strikes would last only two or three days and involve long range bombers like this one we saw. They would fire cruise missiles that are stealthy, accurate and deadly. The syrian regime would never see them coming. Military commanders are now awaiting orders from the president, but that will not likely come until u.N. Investigators are out of damascus several days from now. Diane? Back here at home today app entire nation remembered a dream

This transcript has been automatically generated and may not be 100% accurate.

{"id":20101309,"title":"Fear Growing in the Middle East Over Syria, Gas Masks Handed Out in Israel","duration":"2:13","description":"Chemical attacks in Syria confirmed; potential targets identified if U.S. strikes. ","section":"WNT","mediaType":"Default"}